Via USA Today:
A Naval hospital in San Diego is on lockdown after an anonymous caller reported an active shooter inside a building with other gunmen possibly on the way, according to a Defense official.
The call matched another report of a patient seen with a weapon, according to the official who was not authorized to speak publicly. All personnel were ordered to shelter in place and police were responding to the scene.
A similar report that turned out to be false came at the same naval hospital in January.
Officials scoured buildings and grounds with dogs in January but found no evidence of a gunman or shots having been fired.